The major aim of this experiment is to determine whether a daily early afternoon nap for elderly people will help promote high levels of evening alertness and performance, thus preventing unwanted early evening sleepiness (UESS). Specifically, a within-subject design (n=32, 16m, 16f, age 70y-90y) will be used to test whether a 90-minute afternoon nap regimen, imposed for 14 days at home and for 3 days in the laboratory, will have the effect of increasing evening alertness, improving evening performance, delaying the self-selected bedtime and/or eliminating evening naps.